Region of Interest Reconstruction of Tomographic Images using Filter Banks

Abstract

A new technique for ROI image reconstruction from projections using filter banks is reported in this paper. It is known that the convolution back projection operator, used for reconstruction of images from 1D-projections, has a non-local filter which requires global projection data. In X-ray tomography, the exposure time of the object to harmful radiation is thereby increased. Recently, it has been proved that this filtering operation can be done on a chosen wavelet function instead of the projections. This localizes the filter and leads to ROI image reconstruction with reduced projections. This concept was extended using 2D and 1D MRA filter banks, in which the filters are combined with the non-local CBP filter to get short length filters. In this paper it is proved that the presence of unwanted information in all previous algorithms is due to aliasing and a new technique is proposed for reconstruction without any aliasing. The proposed scheme is implemented using Shepp-Logan phantom head image and the performance is compared.

Indexing terms:

• Convolution back projection
• Region of interest
• Multiresolution analysis
• Discrete parameter
• Wavelet transform
• Radon transform
• Non local filter

Additional information

Notes on contributors

Gomathi Sankar

Gomathi Sankar graduate from REC, Guindy (Tamil Nadu) in 1995 and did his MTech, from Indian Institute of Technology, Kanpur in 1997. Currently, he is working in the Multimedia Group of Silicon Automation System, Bangalore.

Sumana Gupta

Sumana Gupta received BE, ME from Indian Institute of Science, Bangalore; PhD from Imperial College of Science and Technology, London (UK) in 1976. Currently on the Faculty of the Department of Electrical Engineering, Indian Institute of Technology, Kanpur, India. Current research interests are in the area of image processing, video coding, data compression and multimedia information systems.